1. Field of the Invention
The present invention relates to a handheld computerized device with a touchpad installed on the back panel or other portion of the body other than the display screen. More particularly, the invention relates to a method and graphical user interface that enables the user to see the user's finger position and motion from the back of the device, superimposed on a keyboard layout on the display screen. This makes it easier for a user to input keystrokes and mouse actions from a touchpad that is installed on the back panel or other portion of the handhold device.
2. Description of the Related Art
Handheld computerized devices (i.e. devices equipped with microprocessors and sophisticated displays) such as cell phones, personal digital assistants (PDA), game devices, tabletPCs (such as iPad), etc., are playing a more and more important role in everyday life, and are becoming more and more indispensible. With the advance of technology, and improvements in the handheld computerized devices' processing power, both function, and memory space is increasing at an amazing pace. Meanwhile the size of the handheld computerized devices continues to get smaller and smaller.
To meet this challenge, the designers of handheld computerized devices typically use two approaches. One approach is to make the keyboard keys smaller and smaller, minaturizing the keys. Additionally the keyboard keys may be given multiple functions—i.e. overloaded, and more complex function keyboard keys may be introduced as well.
The other approach is to use touch screen keyboards, or so called “soft keys”, on the front panel. Here a user may use a stylus pen or finger to select the soft keys through a graphical user interface. However due to the optical illusions introduced by the display screen, and the fact that the user's fingers often are on top of the various display screen soft keys (hence blocking them from direct viewing), the soft keys cannot be too small. Another problem is that when the soft keys are too small, often a single finger press will activate multiple keys. As a result, the designer may have to divide the keys into different groups and hierarchies, and only display a small number of keys on the screen.
Both current approaches have some severe drawbacks: the user input area occupies a significant portion of the front panel, and the user input process, although requiring a large amount of user attention to operate, still is very error prone.
Often a user has to use one hand to hold the handheld computerized device, and use the other hand to input data, thus occupying both hands. A user will often have to go through a long sequence of key strokes, and switch back and forth among different user interface screens, in order to complete a fairly simple input. As a result, there is a significant learning curve for a user to learn the overloaded keys, function keys, key grouping, and key hierarchies in order to operate the handheld computerized devices efficiently.
Although previous workers, such as Libenow et. al., U.S. Pat. No. 6,909,424 proposed designs with sensors on the back of the device and representations of the user's fingers on the front of the device, this prior art work failed to adequately describe a procedure by which the indicia of the user's fingers or hands are displayed on the display panel.
Other previous workers, such as Westerman et. al., in US patent application 2008/0211766 described systems in which image sensors would obtain an image of the user's fingers while operating the device, and use this image data to better determine which real or virtual keys the user's fingers were striking Such methods rely, however, on image sensors that are positioned in such a way as to be capable of viewing the tips of the user's fingers. This type of image sensor placement is often difficult to implement on many types of handheld user computerized devices. Another drawback of the Westerman approach is that it is difficult to implement in low light situations. This approach may also be difficult to implement in situations where there is limited smooth and flat desk or table space.